Acute and Chronic Diarrhea

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Definitions & Types - The Runs Rundown

  • Duration Classifications:
    • Acute Diarrhea: Lasts <14 days.
    • Persistent Diarrhea: Lasts 14-29 days.
    • Chronic Diarrhea: Lasts ≥30 days.
  • Major Pathophysiological Types: Osmotic, Secretory, Inflammatory, Dysenteric (📌 OSID).
  • Stool Osmotic Gap (SOG): $290 - 2 \times (Stool\ Na^+ + Stool\ K^+)$.
    • Osmotic: SOG > 100 mOsm/kg.
    • Secretory: SOG < 50 mOsm/kg.

⭐ In India, Rotavirus is the most common cause of severe dehydrating diarrhea in children <2 years.

Acute Diarrhea: Causes & Signs - Bugs & Bellyaches

Common Pathogens & Features:

CategoryPathogenStoolKey Features
ViralRota, NoroWateryVomiting, fever
BacterialETEC, EPECWatery📌 ETEC: Trav; EPEC: Peds
EHEC, EIECBloody📌 EHEC: HUS; EIEC: Inv
V. choleraeWateryProfuse, rice-water, painless
ShigellaBloodyMucoid, fever, tenesmus
SalmonellaBloody/WFever
CampylobacterBloodyFever, abd pain
ParasiticGiardiaWateryFoul, malabsorption
CryptosporidiumWateryProlonged (imm.comp.)
E. histolyticaBloodyFlask ulcers

WHO Dehydration Assessment: WHO Dehydration Assessment and Treatment Chart

  • No Dehydration: <5% wt loss. Alert, drinks normally.
  • Some Dehydration: 5-10% wt loss. Restless, irritable, drinks eagerly.
  • Severe Dehydration: >10% wt loss. Lethargic, sunken eyes, drinks poorly/unable.

Red Flags:

  • Persistent vomiting
  • Severe dehydration signs
  • Bloody stools
  • High fever
  • No improvement >48h

Etiological Approach:

Acute Diarrhea: Management - Quenching The Thirst

Primary goal: Rehydration using Oral Rehydration Solution (ORS). WHO-ORS Composition (mOsm/L):

ComponentStandardLow Osmolarity
Sodium (Na)9075
Potassium (K)2020
Chloride (Cl)8065
Citrate1010
Glucose11175
Total Osmolarity311245

Dehydration Management Plan:

  • Zinc: Supplement 10mg daily (<6mo) or 20mg daily (>6mo) for 14 days.
  • Antibiotics: Indicated for dysentery (shigellosis), suspected cholera, or specific pathogen.
  • Avoid: Antidiarrheals (e.g., loperamide) and antiemetics are generally not recommended.
  • Nutrition: Continue breastfeeding/age-appropriate diet; avoid BRAT diet.
  • Prevention: Hand hygiene, safe water, Rotavirus vaccination.

⭐ Zinc supplementation in acute diarrhea reduces duration and severity of the episode and prevents future episodes.

Chronic Diarrhea: Etiology - The Long Haul

Defined as diarrhea lasting ≥30 days.

Common Causes & Stool Characteristics in Indian Children:

EtiologyKey FeaturesStool Type
Toddler's DiarrheaThriving child, undigested food particlesWatery, loose
Post-infectiousFollows acute GE, persistent mucosal damageWatery
Lactose IntoleranceBloating, cramps, resolves with lactose removalWatery, frothy
Celiac DiseaseFTT, villous atrophy, gluten-sensitiveFatty, bulky
Cow's Milk Protein AllergyVomiting, eczema, blood in stool (infants)Watery, bloody
IBD (Crohn's, UC)Abdominal pain, weight loss, bloody stoolsBloody, mucoid
Cystic FibrosisFTT, respiratory sx, ↓ fecal elastaseFatty, foul
ImmunodeficiencyRecurrent infections, opportunistic pathogensVariable
  • Celiac disease
  • H (H.pylori - not a cause, but a common GI differential)
  • Rotavirus (post-infectious)
  • Other (Cystic Fibrosis, IBD)
  • Nutrition (Toddler's diarrhea)
  • Intolerance (Lactose)
  • Cow's milk protein allergy

Villous Atrophy vs Healthy Intestine

⭐ Toddler’s diarrhea is characterized by painless passage of loose stools with undigested food particles in a thriving child.

Chronic Diarrhea: Investigation - Detective Work

⭐ Elevated IgA anti-tissue transglutaminase (anti-tTG) antibodies are highly specific for Celiac Disease screening.

High‑Yield Points - ⚡ Biggest Takeaways

  • Acute diarrhea: most commonly viral (e.g., Rotavirus); Oral Rehydration Solution (ORS) is the cornerstone of management.
  • Persistent diarrhea lasts >14 days; requires investigation for secondary infections or malabsorption.
  • Chronic diarrhea lasts >4 weeks; consider Celiac disease, lactose intolerance, or Inflammatory Bowel Disease (IBD).
  • Red flag signs in diarrhea include blood or mucus in stool, severe dehydration, persistent vomiting, and failure to thrive.
  • Celiac disease screening involves IgA anti-tissue transglutaminase (anti-tTG) antibodies; diagnosis confirmed by duodenal biopsy.
  • Lactose intolerance can be diagnosed by a hydrogen breath test or clinical improvement with lactose elimination.
  • Toddler's diarrhea (chronic non-specific diarrhea) is typically benign, often linked to excessive fruit juice intake or a low-fat, high-fiber diet.

Practice Questions: Acute and Chronic Diarrhea

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What is the next best investigation for a patient with suspected jejunal atresia on x-ray?

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